Variable resistor of sliding type

ABSTRACT

IMPROVEMENTS ON A VARIABLE RESISTOR OF THE SLIDING TYPE AND MORE PARTICULARLY THE STRUCTURE OF FITTING A SLIDER AND A CONTACT ELEMENT TO A RESISTOR IS DISCLOSED, PREVENTING THE LATERAL ROLLING OF THE SLIDER AND MAKING THE FITTING   POSITION OF THE CONTACT ELEMENT ADJUSTABLE TO CONTROL THE VALUE OF RESISTANCE SIMPLY.

Feb- 23, 1971 KATsUMl lcHlKAwA ET AL VRIABLE .RESISTOR OF SLDING TYPE ssheets-shea 1 Filed Sept. 20, 1968 Feb. 23; 1971 KATSUMl |CH|KAWA ETAL3,566,330

v VARIABLE REsIsToR oF sLIDING TYPE Filed Sept. 20, 1968 v 3Sheets-Sheet 2 F/G. .9 I y CP/03 Feb. 23,1971 `KATSUMI lcHlKAwA ET Al.3,566,330

I f VARIABLE REsIsToR oF sLIDING TYPE Filed sept. 2o, .196e ssheets-sheet s United States `Patent O U.S. Cl. 338-133 8 ClaimsABSTRACT F THE DISCLOSURE Improvements on a variable resistor of thesliding type and more particularly the structure of tting a slider and acontact element to a resistor is disclosed, preventing the lateralrolling of the slider and making the tting position of the contactelement adjustable to control the value of resistance simply.

BACKGROUND OF THE INVENTION Field of the Invention This inventionrelates in general to a variable resistor of the sliding type and moreparticularly to a variable resistor of the sliding type in which themechanism of a slider is improved and the position of a contact elementfitted to the slider is made adjustable after assembling.

Description of the Prior Art A prior art variable resistor of thesliding type has a structure in which slider riding on a guide rodprovided in the center of a case is slided by manipulating an actuatinglever. When a lateral force is applied to the actuating lever, itsuffers a large deflection. A minute crack on the surface of the guiderod causes roughness or blockage during manipulation so that smoothsliding is not obtainable. Such a lateral dellection has made itimpossible to give a constant pressure of Contact element on theresistance element.

Generally, a variable resistor of the duplex sliding type is often usedas volume or tone control of a stereo set. In this case, unless theresistances in both variable resistors vary equally, a true stereo isnot obtained as the volume or the tone of the speakers on both sidesdiffers. A certain unbalance is brought forth depending on the variationof resistance characteristic and the dimension of the resistanceelement. However, it is errors in assembling the variable resistor whichmainly influence the unbalance. A defect of the conventional duplex typevariable resistor is that the position of a contact element with respectto the resistor has a large influence on the value of resistance andcauses a deviation between both resistors.

SUMMARY OF THE INVENTION Therefore, one object of this invention is toprovide a variable resistor of the Asliding type obviating theabovementioned roughness and blockage and applying a constant pressureof the contact element on the resistance element.

Another object of this invention is to provide a variable resistor ofthe sliding type in which the position of a contact element fitted tothe slider is made adjustable after assembling so that any error thatmight occur during assembly is eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectionalfront view of a prior art variable resistor of the sliding type.J

ice

FIG. 2 is a longitudinal sectional front view of a variable resistor ofthe sliding type according to one embodiment of this invention.

FIG. `3 is a perspective view showing the disassembled main portion ofthe above variable resistor of the sliding type.

FIG. 4 is a longitudinal sectional front View of a variable resistor ofthe sliding type according to another embodiment of this invention.

EFIG. 5 is a perspective view showing the disassembled main portion ofthe above variable resistor of the sliding type.

FIG. 6 is a top view of a variable resistor of the sliding typeaccording to a further embodiment of this invention.

'FIG. 7 is a cross-sectional view of the above Variable resistor of thesliding type.

FIG. 8 is a perspective view showing the disassembled main portion ofthe above variable resistor of the sliding type.

FIG. 9 is a longitudinal cross-sectional view of a variable resistor ofthe sliding type according to another embodiment of this invention.

FIG. 10 is a perspective view showing the disassembled main portion ofthe above variable resistor of the sliding type.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A prior art variable resistorof the sliding type will be explained hereinafter with reference to FIG.l. 1 is a metal case made by metal plate processing, a guide window 2being formed in one portion of the top surface and a base 3 being ttedon the bottom wall. 4 is a slider made of a rectangular insulatingmaterial with an actuating lever r5 on its top surface penetrating theguide window 2 and with a groove portion in the bottom surface riding ona guide rod `6 positioned in the center of the case. 7 shows mailsprovided in the corner of the top surface of the slider 4 to touch theinn'er top surface of the case 1. 8 and 8 are contact elements havingcontact portions 9, 9', 10 and 10' tted to the bottom of the slider 4.These contact portions are slid on the resistance elements 11 and 11'and contact plates 12 and 12. which are provided on the base 3 inparallel with one another. 13, 13', '14 and 14' are wiring terminalsprovided outside the base 3 and are connected to the ends of resistanceelements -11 and 11' and contact plates 12 and 12 respectively.

In this structure, the slider 4 riding on the guide rod 6 is slid bymanipulating the actuating lever 5. So, when a lateral force is appliedto the actuating lever 5, it suffers a large deflection. Further, minutecracks existing on the surface of the guide rod 6 cause roughness orblockage during manipulation and prevent a smooth slide. The lateraldeflection of the slider presses down the contact elements 8 and 8'thereunder making it difficult to give a constant pressure of thecontact element on the resistance element.

This invention eliminates the above-mentioned roughness and blockage andprovides a structure in which a constant pressure is kept applied on theresistance element.

Explanation of one embodiment of this invention will be made hereunderwith reference to FIGS. 2 and 3.

-15 is a metal case made of metal plate with a guide window 16 on oneportion of the top surface. A base 18 made of molded material withprotrusions 17 and 17 on both sides of the top surface is fitted to thebottom surface of the case 1S. 19 is a slider of insulating material,the bottom surface of which is disposed on the protrusions 17 and 17. 20is a rectangular projection provided on the top of the slider 19A andslidingly fitted into the guide window 16. Protrusions 21 and 21 on bothsides of the slider 19 contact with `the inner top surface of the case15. The bottom surface of the sliding body 19 is on the protrusions 17and 17 by manipulating an actuating lever 22 provided on the rectangularprojection 20. Contact elements 23 provided under the slider and havinga contact portion is arranged to slide on a resistance element 24 andcontact plate 25 which are provided in parallel with each other on thebase 18. 26 and 27 are wiring terminals provided outside the case 15 andconnected to the end portions of the resistance element 24 and thecontact plate 25 respectively.

As is seen in the above-mentioned structure of the inventive variableresistor of the sliding type, since the bottom surface of the slider 19is positioned on the protrusions 17 and .17' of the base 18, a constantpressure is always applied on the resistance element 24. Further, asthese sliding portions are made of molded material, they provide for avery smooth slide action. Even if a lateral force is applied to theactuating lever 22, the rectangular projection 20 provided on the slider19 touches the guiding window thereby to prevent the rolling of theactuating lever 22.

Next, explanation of another embodiment of this invention will be madewith reference to FIGS. 4 and 5.

In these figures, 15 is a metal case made of sheet metal, a guide window16 being formed in one portion of the top surface. A base 18 of moldedmaterial having protrusions 17 and 17' on both sides of the top surfaceis provided under the case 15. 19 is a slider of insulating material. Anactuating lever 22 is provided on the top of the slider, penetrating theguide window 16. Both sides of the bottom surface of the slider 19 areshaped into ridges 28 and 28 which are made to contact with theprotrusions .17 and :17. The protrusions 21 and 21 provided on bothsides of the top surface of the slider 19 contact with the inner topsurface of the case 15. The ride portions 28 and 28' are slid bymanipulating the actuating lever 22. Contact elements 23 provided underthe slider 19 and having a contact portion are arranged to slide on aresistance element 24 and a contact plate 25. 26 and 27 are wiringterminals provided outside the base 18 and connected to the end portionsof the resistance element 24 and the contact plate 25 respectively.

As is seen in the structure of the above inventive variable resistor ofthe sliding type, even if a lateral force is applied tothe actuatinglever 22, the contact between the ridge portions 28 and 28 on both sidesof the bottom surface of the slider 19 and the protrusions 17 and 17'provided on both sides of the top surface of base 18 can prevent thelateral rolling of the actuating lever 22. Further, since these slidingportions are made of molded material, the sliding action becomesextremely smooth.

As is evident from the above description, the lateral movement of theactuating lever can be prevented by a simple structure, and a smoothsliding action is obtained. Therefore, the practical merit of thisinvention is very large.

Generally, a variable resistor of the duplex sliding type is often usedfor the volume or tone control in a stereo set. In this case, unless theresistances of the two variable resistors vary equally duringadjustment, both speakers differ in volume or tone so that any truestereo is not obtained. The variation of resistance characteristic andthe dimension of the resistance element cause a certain unbalance.However, it is the errors in the step of assembling that have a largeinfluence on such an unbalance. Namely, the position of a contactelement with respect to the resistance element occasionally suffers alarge deviation.

This invention eliminates such a defect using a simple structure,whereby the contact position is adjustable after the resistors areassembled.

Explanation of another embodiment of this invention will be madehereunder with reference to FIGS. 6 to 8.

In these figures, 101 is a base made of an insulator, on which tworesistance elements 102 and 103 and two contact plates 104 and 105 areprovided. Pairs of resistance elements and contact plates 102 and 104,and 103 and 105, constitute individual resistors. The base 101 iscovered with a case 106 made of metal sheet bending processing. Anelongated hole 107 is formed in the top surface of the case 106. Aslider 109 with an actuating lever 108 penetrating the elongated hole107 is disposed in the case 106. Two contact elements 110 and 111 -arefitted on the bottom surface of the slider 109 to be in contact with theresistance elements 102 and 103 and the contact plates 104 and 105. Asshown in FIG. 8, these contact elements 110 and 111 are fixed intoprotrusions 112 provided on the bottom surface of the slider 109. One ofthem 110 is perfectly fixed by the protrusions 112 while the otherelement 111 is held by a cut-and-raised opening 113 slightly larger thanthe size of the protrusions 112. A through hole 115 is perforated in theextended portion 1'14 of the contact element 111 and positioned on acutaway portion 116 which is to be aligned with the elongated hole 107.Therefore, the through hole 115 can be seen through from outside by wayof the Ielongated hole 107. A slender rod is inserted through the hole115 and moved in the lateral direction so that the position of thecontact element 111 with respect to the resistance element 103 may shiftand the resistances of both contact elements 110 and 111 will be equal.

Lastly, a further embodiment of this invention will be explained withreference to FIGS. 9 and 10, in which 101 is a base made of aninsulating material. Two resistive elements 102 and 103 and two contactplates 104 and 105 are fitted on the base 101. Pairs of resistanceelements and contact plates 102 and 104, and 103 and 105 constituteindividual resistors. The base 101 is covered with a case 106 made ofmetal sheet bending processing. An elongated hole 107 is formed in thetop surface of the case 106. A slider 109 with an actuating lever 108penetrating the elongated hole 107 is disposed in the case 106. Twocontact elements 110 and 111 are fitted on the bottom surface of theslider 109 and contact with the resistance elements 102 and 103 and thecontact plates 104 and 105. As shown in FIG. l0, these contact elements110` and 111 are fixed into the protrusions 112 provided on the bottomsurface of the slider 109. One of them 110 is perfectly fixed by theprotrusion 112 while the other 111 is held by an elliptic fitting hole118 having a slightly larger size than that of the protrusion 112.Namely, the contact element 111 is fixed into the protrusion 112 but canbe slid. A through hole 115 is perforated in the extended portion 114 ofthe contact element 111 and positioned on a cutaway portion 116 which isto be aligned with the elongated hole 107. Therefore, the through hole115 can be seen through from the outside by way of the elongated hole107. A slender rod is inserted through the hole 115 and moved in thelateral direction so that the position of the contact element 111 withrespect to the resistance element 103 may shift and the resistances ofboth contact elements 110 and `111 will be equal.

As is seen from the `above-mentioned structure of the inventive slidetype variable resistor, a contact element is fixed into a protrusionprovided under the slider by either a cut-and-raised opening or inelliptic hole which has a slightly larger size than that of theprotrusions. The through hole formed in one portion of the contactelement is transparent. So, the position of the contact element withrespect to the resistance element can be varied through this hole. Inthe case of a variable resistor of the duplex sliding type theresistances of the two contact elements can be adjusted to be equal.Therefore, this variable resistor of the duplex sliding type is veryeffective if employed in a stereo set. Also, a variable resistor of thesingle sliding type though not shown in the above embodiments is usefulas a minute adjustment of the resistance is possible. Due

to such a simple structure with only holes in the contact elements thesevariable resistors of the sliding type can be manufactured cheaply.Therefore, the practical advantage of this invention is very large.

What is claimed is:

1. A variable resistor of the sliding type comprising a case having aguide window in one portion thereof; a base of molded material providedon the bottom surface of said case and having protrusions on both sidesof the top surface; a slider of insulating material arranged in saidcase so that the bottom surface is positioned on said protrusions ofsaid base; a protrusion located on the bottom surface of said sliderdisposed between said case and said base on 'which resistance elementsand contact plates are provided; a contact element having acut-andraised opening with a slightly larger dimension than that of saidprotrusion xed into said protrusion, one portion of said contact elementbeing provided with a through hole which can be seen through by way ofan elongated hole formed in said case; and a rectangular projectionprovided on the top surface of said slider to be slidingly tted intosaid guide window.

2` A Variable resistor of the sliding type comprising a case having aguide window in one portion thereof; a base of moulded material providedon the bottom surface of said case and having protrusions on both sidesof the top surface; a slider of insulating material arranged in saidcase so that the bottom surface is positioned on said protrusions ofsaid base; a protrusion located on the bottom surface of said sliderdisposed between said case and said base on which resistance elementsand contact plates lare provided; a contact element having an elliptichole with a slightly larger dimension than that of said protrusion fixedinto said protrusion, one portion of said contact element being providedwith a through hole which can be seen through by way of an elongatedhole formed in said case; and a rectangular projector provided on thetop surface of said slider to be slidingly fitted into said guidewindow.

3. A variable resistor of the sliding type according to claim 2, whereina cutaway portion is formed in one portion of said contact element so asto be seen through by way of said elongated hole formed in said case.

4. A Variable resistor of the sliding type according to claim 1 whereina cutaway portion is formed in one portion of said contact element so asto be seen through by way of said elongated hole formed in said case.

5. A Variable resistor of the sliding type comprising a case having aguide window in one portion thereof, a base of molded material providedon the bottom surface of said case and having molded protrusions on bothsides of the top surface, a slider of insulating material having cutawayportions on both sides of the bottom surface of said slider, said sliderbeing arranged in said case in such a manner that said cutaway portionsmay engage slidably with said protrusions provided on said base; furthercornprising a protrusion on the bottom surface of said slider disposedbetween said case and said base on which resistance elements and contactplates are provided, and a contact element having a cut-and-raisedopening with a slightly larger dimension than that of said protrusionXed into said protrusion, one portion of said contact element beingprovided with a through hole which can be seen through by way of anelongated hole formed in said case.

6. A variable resistor of the sliding type comprising a case having aguide window in one portion thereof, a base of molded material providedon the bottom surface of said case and having molded protrusions on bothsides of the top surface, a slider of insulating material having cutawayportions on both sides of the bottom surface of said slider, said sliderbeing arranged in said case in such a manner that said cutaway portionsmay engage slidably -with said protrusions provided on said base;further comprising a protrusion on the bottom surface of said sliderdisposed between said case and said base on which resistance elementsand contact plates are provided, and a contact element having anelliptical hole with a slightly larger dimension than that of saidprotrusion fixed onto said protrusion, one portion of said contactelement being provided with a through hole which can be seen through byway of an elongated hole formed in said case.

'7. A variable resistor of sliding type according to claim 5, wherein acutaway portion is formed in one portion of said contact element so asto be seen through by way of said elongated hole formed in said case.

8. A variable resistor of sliding type according to claim 6, wherein acutaway portion is formed in one portion of said contact element so asto be seen through by way of said elongated hole formed in said case.

References Cited UNITED STATES PATENTS 2,242,327 5/ 1941 Rubinstein338-183 2,954,537 9/1960 Scott, Jr., et al 338-180 3,178,664 4/1965Thoele 338-183 3,238,488 3/1966 Langenbach et al. 338-183X 3,271,7219/1966 Gordon 338-180X 3,412,361 11/1968 Lovejoy et al. 338-183X THOMASJ. KOZMA, Primary Examiner U.S. Cl. X.R.

